1645640002 has 4 divisors (see below), whose sum is σ = 2468460006. Its totient is φ = 822820000.

The previous prime is 1645639987. The next prime is 1645640023. The reversal of 1645640002 is 2000465461.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 2000465461 = 44101 ⋅45361.

It can be written as a sum of positive squares in only one way, i.e., 1361683801 + 283956201 = 36901^2 + 16851^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 411409999 + ... + 411410002.

Almost surely, 2^1645640002 is an apocalyptic number.

1645640002 is a deficient number, since it is larger than the sum of its proper divisors (822820004).

1645640002 is an equidigital number, since it uses as much as digits as its factorization.

1645640002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 822820003.

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 1645640002 is about 40566.4886575114. The cubic root of 1645640002 is about 1180.6240120924.

The spelling of 1645640002 in words is "one billion, six hundred forty-five million, six hundred forty thousand, two".